def flist(l):
    l.append(0)
    print(id(l))    # 每次打印的id相同
    print(l)


ll = []
print(id(ll))
flist(ll)   # [0]
flist(ll)   # [0,0]

print("=" * 10)


def fstr(s):
    print(id(s)) # 和入参ss的id相同
    s += "a"
    print(id(s))  # 和入参ss的id不同，每次打印结果不相同
    print(s)


ss = "sun"
print(id(ss))
fstr(ss)    # a
fstr(ss)    # a

def clear_list(l):
    l = []

ll = [1,2,3]
clear_list(ll)
print(ll)

def fl(l=[1]):
    l.append(1)
    print(l)
fl()
fl()
